VB.Net - BitArray Class

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The BitArray class manages a compact array of bit values, which are represented as Booleans, where true indicates that the bit is on (1) and false indicates the bit is off (0).

It is used when you need to store the bits but do not know the number of bits in advance. You can access items from the BitArray collection by using an integer index, which starts from zero.

Properties and Methods of the BitArray Class

The following table lists some of the commonly used properties of the BitArray class:

PropertyDescription
CountGets the number of elements contained in the BitArray.
IsReadOnlyGets a value indicating whether the BitArray is read-only.
ItemGets or sets the value of the bit at a specific position in the BitArray.
LengthGets or sets the number of elements in the BitArray.

The following table lists some of the commonly used methods of the BitArray class:

S.NMethod Name & Purpose
1Public Function And ( value As BitArray ) As BitArray
Performs the bitwise AND operation on the elements in the current BitArray against the corresponding elements in the specified BitArray.
2Public Function Get ( index As Integer ) As Boolean
Gets the value of the bit at a specific position in the BitArray.
3Public Function Not As BitArray
Inverts all the bit values in the current BitArray, so that elements set to true are changed to false, and elements set to false are changed to true.
4Public Function Or ( value As BitArray ) As BitArray
Performs the bitwise OR operation on the elements in the current BitArray against the corresponding elements in the specified BitArray.
5Public Sub Set ( index As Integer, value As Boolean )
Sets the bit at a specific position in the BitArray to the specified value.
6Public Sub SetAll ( value As Boolean )
Sets all bits in the BitArray to the specified value.
7Public Function Xor ( value As BitArray ) As BitArray
Performs the bitwise eXclusive OR operation on the elements in the current BitArray against the corresponding elements in the specified BitArray.

Example:

The following example demonstrates the use of BitArray class:

Module collections
   Sub Main()
      'creating two  bit arrays of size 8
      Dim ba1 As BitArray = New BitArray(8)
      Dim ba2 As BitArray = New BitArray(8)
      Dim a() As Byte = {60}
      Dim b() As Byte = {13}
      'storing the values 60, and 13 into the bit arrays
      ba1 = New BitArray(a)
      ba2 = New BitArray(b)
      'content of ba1
      Console.WriteLine("Bit array ba1: 60")
      Dim i As Integer
      For i = 0 To ba1.Count
          Console.Write("{0 } ", ba1(i))
      Next i
      Console.WriteLine()
      'content of ba2
      Console.WriteLine("Bit array ba2: 13")
      For i = 0 To ba2.Count
          Console.Write("{0 } ", ba2(i))
      Next i
      Console.WriteLine()
      Dim ba3 As BitArray = New BitArray(8)
      ba3 = ba1.And(ba2)
      'content of ba3
      Console.WriteLine("Bit array ba3 after AND operation: 12")
      For i = 0 To ba3.Count
          Console.Write("{0 } ", ba3(i))
      Next i
      Console.WriteLine()
      ba3 = ba1.Or(ba2)
      'content of ba3
      Console.WriteLine("Bit array ba3 after OR operation: 61")
      For i = 0 To ba3.Count
          Console.Write("{0 } ", ba3(i))
      Next i
      Console.WriteLine()
      Console.ReadKey()
   End Sub
End Module

When the above code is compiled and executed, it produces the following result:

Bit array ba1: 60 
False False True True True True False False 
Bit array ba2: 13
True False True True False False False False 
Bit array ba3 after AND operation: 12
False False True True False False False False 
Bit array ba3 after OR operation: 61
True False True True False False False False 


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